America is building a border barrier that is both too tight and not tight enough

FOR the past four years Steve Johnston has been dropping food, water and socks in the Sonoran desert. They are intended for illegal immigrants, who have often been walking for three or four days. Demand has never been greater. Recently Mr Johnston left 80 gallons of water beside a popular trail, and returned the next day to find all but eight gallons gone. He has encountered 40-strong groups walking in broad daylight. It is, oddly, proof that America's growing border fence is having an effect on illegal immigration.

The reason so many immigrants are tramping through Mr Johnston's neighbourhood can be found 12 miles to the south-west. Around Sasabe, steel cylinders have been sunk into the desert to create an imposing fence. That has blocked a popular migration route and driven people east. No More Deaths, a humanitarian group, has drawn up a map of migration routes based on how much water and food disappears. It looks like a leaf skeleton—a pattern of interlocking lines snaking north through the desert, then east to just above a checkpoint. From there, immigrants are driven to Tucson and Phoenix, whence they travel to wherever there are jobs.

By the end of this year the American government is supposed to have erected 670 miles of fencing along the 2,000-mile border with Mexico. Roughly half of the barrier is designed to stop everything bigger than a jackrabbit; the other half will let people through but stop vehicles. It is just part of a drive, stepped up in the past two years, to clamp down on illegal immigration and drug-smuggling. The Border Patrol is swelling from fewer than 6,000 officers in 1996 to more than 18,000 by next year. Unmanned watchtowers bristling with cameras and heat sensors are being developed. Finally, checks at proper border crossings are becoming more rigorous.

The fence is behind schedule and well over budget, and the network of electronic watchtowers is even further from deployment. But enough has been built, strengthened and staffed to make it clear what kind of border the next president will inherit. America is creating a barrier that is at once much too porous and rather too tight.

Until fairly recently the western half of the US-Mexican border was largely abstract. “As far as the eye can reach stretches one unbroken waste, barren, wild, and worthless,” wrote John Russell Bartlett, who surveyed the area for the American government in the 1850s. The border was marked at first by piles of stones, then by concrete obelisks. Over time the occasional barbed-wire fence went up, but the border was permeable. “You could ride your bike across it,” says Michael Gomez, who grew up five blocks from the border and is now mayor of Douglas, Arizona.

Before the early 1990s those who wanted to cross illegally generally headed for the cities of Tijuana and Juárez. They would wait until night, scale the puny fence and dash for San Diego and El Paso. It was a simple matter of outnumbering the Border Patrol. Then, beginning in 1993, taller fences began to go up in the busiest sections of California and Texas. The assumption was that physical barriers would stop crossers in the cities, and geography would stop them elsewhere.

The first assumption turned out to be correct: between 1994 and 2000 the number of apprehensions around San Diego plunged by two-thirds. The second did not. Rather than giving up, immigrants converged on the border's thinly-policed midsection, braving sun and snakes on long hikes through the desert. In the late 1990s the number of apprehensions shot up in the 260-mile Tucson sector (see chart). So did deaths. Raquel Rubio-Goldsmith of the University of Arizona reckons 125 people died trying to cross the desert in the 1990s. Since 2000 the death toll has been more than 1,000. By contrast, fewer than 300 people died attempting to cross the Berlin Wall in its 28-year history.

As illegal immigrants began to funnel through Arizona, attitudes hardened. In 2004 the state's voters approved a measure intended to deny public benefits to illegals. It was reminiscent of an initiative that Californians had supported in the previous decade, when their state was the central conduit for immigration. Two years later Janet Napolitano, Arizona's Democratic governor, harried the federal government into sending National Guard troops to the border. In 2007 she signed a law stepping up penalties on businesses that knowingly employed illegal workers.

Even political moderates have become advocates for the border fence. Arizona's senior senator is a good example. John McCain has long been an advocate for “comprehensive” immigration reform—Washington-speak for a bill that would allow some illegal immigrants to become citizens. In the past few months, though, he has insisted that the border must be sealed first. Mr McCain's change of heart was probably necessary to get him through the Republican primaries. Yet it is also in harmony with the more strident tone of public opinion in his home state.

Opinions are more nuanced closer to Mexico. David Walker, whose family owns a ranch that spans ten miles of the Arizona-Sonora border, describes the fence as “kind of a Band-Aid”. The new pedestrian fence that edges his property has stemmed the flow of immigrants but not stopped it. By means of ladders, blow-torches and screwdrivers, immigrants are still getting through. They drop litter, which is harmful (“Cattle are dumb—they'll eat plastic water bottles”) and break cisterns trying to get fresh water. But Mr Walker regards such things as fairly minor nuisances.

He is more concerned about the drug-traffickers who once tried to run him over. So are others. “I'm not a bit afraid of the little Mexicans coming across the border to work,” says one woman who runs a ranch near the border. “It's the drug lords that worry me.” She is right to be worried.

New Tijuana moods

Though the drug trade and the violence that goes with it have long been features of the border, the past few years have seen both a rise in violence and a change in its nature. The decision of Felipe Calderón, Mexico's president, to use the army against drug-trafficking gangs has led to an arms race and provoked turf wars along the border, from Tijuana to Matamoros. The city of Nogales, Sonora (across the border from Nogales, Arizona) has seen 72 murders so far this year, compared with 44 in 2007.

Despite talk of a united front, the Mexican authorities are divided over how to tackle the problem. Marco Antonio Martinez Dabdoub, the mayor of Nogales, reckons the federal government ought to be more heavy-handed. “This should be like the famous surge in Baghdad,” he says. Yet Arturo Ramirez Camacho, the head of Nogales's police force, says that the deployment of the army has served only to provoke more violence. It has been hard to replace the 188 officers who have been sacked for corruption.

So far the surge of violence in Mexican border towns has been largely confined to the narcos and the police. One journalist in Nogales estimates that all but one of the murders so far this year have involved someone connected with the drug trade. Alvaro Navarro Gárate, who is in charge of promoting economic development for the city of Juárez, south of El Paso, says the violence has not yet deterred economic investment. Although some executives fret about being kidnapped, the lack of infrastructure is more off-putting.

The rise of organised crime has, however, changed patterns of illegal immigration. Ten years ago people-smuggling was a casual, low-margin business—a “mom-and-pop” operation, as locals call it. As crossing the border became harder, and the coyotes' fees rose from about $500 to more than $2,000, the cartels saw a chance for profit. Many of those who traipse through western Arizona these days do so at the pleasure of the Sinaloa cartel, which also runs drugs across the border (although rarely at the same time as people). Its henchmen can be brutal and dishonest, but they are also pretty good at their jobs.

Counting fish in the sea

The fence is undoubtedly changing patterns of illegal immigration. But is it staunching the flow? The Border Patrol points to the fact that they are catching fewer people. Yet this is a very imperfect measure, rather like estimating the number of fish in the sea from those hauled up in fishermen's nets. The figures do not count those who make it, and they double-count people who keep trying. Remittances to Mexico (see chart above) provide a better picture. These were rising until recently, largely because immigrants began to send more money through formal channels. Now they are falling, but not by much.

For more than ten years, Wayne Cornelius of the University of California at San Diego has been surveying people in high-emigration areas of Mexico. He finds that fewer than half of all would-be illegal immigrants are apprehended on any given trip, and virtually all get through eventually. Mexicans keep trying even though they know the border has become more dangerous. In an unpublished study, Mr Cornelius reports that more than 30% of Oaxacans who plan to steal across the border know somebody who has died trying.

There is a more obvious reason for the recent slowdown in illegal immigration. Construction and landscaping jobs, a common source of employment for Latino immigrants both legal and illegal, have disappeared as the housing market has collapsed. In the past year the Hispanic unemployment rate has risen from 5.4% to 8.0%. Among Hispanics aged 16 to 19 the rate is 22.8%. This deters would-be workers from crossing the border and curtails the ability of people already in America to pay for their relatives to make the trip.

Even if tougher border enforcement has slowed the movement of people, this is not quite the good news it seems. Until recently Mexicans crossed back and forth across the border as work and family demanded. Many years ago Mr Walker's ranch employed a couple of “wetbacks” (the term was not so derogatory as it is today) who would work half a year each, returning to their families in the off-season.

These days, says Ms Rubio-Goldsmith, migration is not circular but linear. If people come they tend to stay, because the cost and difficulty of crossing the border have increased so steeply. They are more likely to bring their families: in the Sonoran desert, says Mr Johnston, about a quarter of the immigrants are women and children. As immigrants put down deep roots in America, villages in Oaxaca that once lacked young men are becoming utterly depopulated. The border fence may be deterring illegal immigration, but it is not reducing the number of illegal immigrants. It is also annoying people.

Not neighbourly

Ten years ago a group of mayors and other officials on both sides of the line formed the Texas Border Coalition. At first it promoted infrastructure projects, but it is now focused on fighting the fence, which almost everyone in South Texas opposes. They say that it is not neighbourly, that it will be a waste of money, and that it will cut Texans off from the Rio Grande, which marks the border in much of the state.

Texas's two Republican senators are keener on the fence, but not much. Kay Bailey Hutchinson wrote an amendment to a spending bill that allowed the Department of Homeland Security greater latitude to decide where it should run. Hardliners argued that this was a way of “gutting” the more specific Secure Fence Act of 2006. The state's other senator, John Cornyn, insists that despite voting for the Secure Fence Act, he doesn't think it will be built.

Such coolness, which may seem strange in such a politically conservative state, is partly a product of economics. During the first half of this year almost 80% of all US-Mexican trade by value passed through Texas. The state's border towns have benefited from NAFTA, which was signed 15 years ago. In July unemployment in the McAllen area was 7.8%, down from 25% in 1990.

Texans' sanguine attitude is also a matter of demography. When the last census was taken, in 2000, Arizona, California and Texas were all between one-quarter and one-third Hispanic. But their border regions look utterly different. Arizona, which is currently America's fastest-growing state, has experienced a wave of white immigrants—the Midwestern “snowbirds”—who have little experience of Latino culture. Its four border counties were 34% Hispanic in 2000. California's two border counties, which are thick with retirees and military families, were just 28% Hispanic. Texas's border counties, by contrast, were 85% Hispanic.

Margaret Dorsey, an anthropologist from the University of Pennsylvania who studies Texas's Lower Rio Grande Valley, says many local families can trace their roots to the mid-18th-century Spanish land-grant programme. Border Texans often speak fluent Spanish and have family and friends on the other side of the river. Students commute from Mexico to the university in El Paso, crossing in a special line that allows them to make it to class on time. They even pay instate tuition rates.

That would be unthinkable in Arizona, where the fence is broadly popular. Yet Arizonans have plenty of gripes about the tightening border. Increasingly, the problem is less the ease of illegal immigration than the difficulty of legal migration.

Roughly three-quarters of people who cross legally from Mexico into Arizona do so in order to shop. As a result, streets close to the fence have become emporiums for things that are more expensive or harder to come by on the other side. That means handbags and children's clothes on the American side, pharmaceuticals and beer on the Mexican side. Because most twin towns are bottom-heavy (Nogales, Arizona has just 20,000 inhabitants, compared with 190,000 in Nogales, Sonora), American towns depend a lot more on Mexican shoppers than the other way around.

Jaime Fontes, the city manager of Nogales, Arizona, reckons Mexican visitors account for roughly 65% of all retail sales in his city. As border officers become more finicky about documents and more zealous in searching vehicles, he worries trade will suffer. Local businessmen say it already has. Chang Lee, who runs a clothes shop just north of the border, explains in fluent Spanglish that Mexicans are spending “too mucho time” waiting to cross, which leaves too little time for shopping. They come running into his shop, clutching fistfuls of bills and begging him to sell them something before they have to return. He estimates that trade has fallen 20-30% in the past year.

In Douglas, the number of vehicle passengers crossing during the first half of this year averaged 321,000 a month—down from 708,000 a month in the first half of 2002. There are more pedestrians, but pedestrians do not buy as much. Manufacturing firms that have set up maquilas in Mexico are suffering too. Two years ago a group of economists calculated that delays at the Tijuana border were costing San Diego County and Baja California more than $4 billion each year.

The tortilla curtain

Over time such gripes are likely to become louder, while complaints about illegal immigration will probably become more muted. Hispanics are slowly acquiring political heft to match their large presence in America; in some states, such as California and New Mexico, they are already powerful enough to punish tough talk. Perhaps more important, Mexico is changing. The country has zoomed towards a first-world birth rate. In the late 1970s the average woman could expect to give birth to five children; now she gives birth to two. As a result, the potential supply of border-crossers will gradually drop.

Yet they will not stop coming. If the Mexican border is, in the old expression, a “tortilla curtain”, it is still floppy enough to allow people and drugs through. A truly impregnable border, of the kind that Mr McCain is demanding, would involve two layers of fencing 2,000 miles long, with a large no-man's land in the middle and plenty of watchtowers. The fence would have to look as it does near San Diego, or as it used to in Berlin. This would involve virtually rasing several towns.

Travelling through Texas in the 1850s, Bartlett encountered plenty of immigrant workers. They found employment in the copper mines for the same reason they now toil in America's building sites and lettuce fields:

“Labour is cheap and abundant in Mexico. At El Paso, Mexican labourers could be had for sixty-two and a half cents per day, they finding themselves; but men could doubtless be procured at even less price.”

While the wage gap between America and Mexico persists, Mexicans will continue to “find themselves” in the American labour force, fence or no fence.